175Khz Inductive Pulse Transmitter - This circuit is discussed in more detail in the Experimenters Journal. The transmitter’s six-inch diameter coil launches powerful magnetic 175KHz ring pulses that can be detected by the circuit below . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

3Khz Filter + Audio Amplifier - This circuit is the audio amp section for a complete optical transmitter. The circuit amplifies and filters the voice audio signals from an electret microphone. The circuit is described in more detail in . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000

40khz TV-VCR Light Source Repeater - This circuit is designed to be placed directly in front of a standard TV or VCR remote. The exiting light pulses produced by the circuit match the pulses from the remote but are about 10 times more powerful. Using the device, the remote can operate a TV or VCR over three times the normal distance. . . Circuit by David A. Johnson P.E.-June, 2000

0.1-3.5GHz Prescaler - This handy prescaler divides input frequency by 1000. it takes maximum input frequency of 3.5GHz and converts it into 3.5MHz that may be measured using standard frequency meter. __

0-500MHZ LM3914 RF Power Meter - RF Measurement has been an expensive work so far the cost f measuring instruments are concerned. Although, the other project, PM2, is hot favorite among radio amateurs for RF Measurement, I wanted something smaller __ Designed by Dinesh Gajjar, VU2F0

0-500MHz PIC16F876 RF Power Meter - RF Measurement has been an expensive work so far the cost of measuring instruments are concerned. RF Meter is based on PIC 16F876 microcontroller, AD8307 and 2x20 LCD display. Full documentation is included. __ Designed by Dinesh Gajjar, VU2F0

1 Transistor FM Transmitter - The photo shows a wireless FM transmitter, pocket radio and yellow disk for size comparisons. Speak into the transmitter and others hear you on any FM radio. The transmitter can be built in an afternoon with simple, affordable and widely available parts. Construction is fun and much can be learned although performance is modest; for example, your voice gets difficult to hear at distances greater than 25 feet. __ Designed by Boondog web site

1 transistor FM transmitter / FM bugging Device - This circuit is basically an oscillator which runs at around 100 MHz. The most important parts of the oscillator are the transistor Q1 and the tuned circuit, which comprises the inductor Ll and the variable capacitor CV1. When the battery is first connected, a brief surge of current flows from the collector to the emitter of Q1, causing an oscillating (i.e: alternating) current to flow back and forth between Ll and CV1. An oscillating voltage therefore appears at the junction of Ll and CV1. The frequency of the oscillation depends on the values of Ll and CV1, so that varying the value of CV1 tunes the oscillations to the exact frequency required.__ CdS Electronic

1 Valve CW transmitter - This transmitter was first constructed in 1987 and provided the author with his first 'real' rig, capable of distances of more than about 100 metres. it performed better than expected, with 250km contacts being commonplace and 2500km being occasionally possible. __ Designed by Peter Parker VK3YE

1 Watt AM transmitter for the 10 meter band (28MHz) - in this project, you will make a simple 3-stage low-power broadcast-type circuit, using a crystal oscillator integrated circuit and an a collector modulated AM oscillator with amplifier. You can connect the circuit to the an electred microphone or amplified dynamic microphone. Using an electred microphone is shown (in gray) in the diagram below. (no amplified dynamic microphone has a to low output voltage to work. at least 100mv is needed). You could also add a LF preamp stage of one transistor to allow connecting a dynamic microphone directly. You'll see that you can receive the signal through the air with almost any AM radio receiver. Although the circuits used in radio stations for AM receiving are far more complicated, this nevertheless gives a basic idea of the concept behind a principle transmitter. Plus it is a lot of fun when you actually have it working! Remember that transmitting on the 10 meter band you'll need a valid radioamateur license! ! __ Designed by Guy Roels ON6MU

1 Watt FM Transmitter Amplifier - This is a 1 Watt FM Transmitter amplifier with a good design that can be used to amplify a RF signal in the 88 – 108 MHz band. it is very sensitive if you use good RF power amplifier transistors, trimmers and coils. it has a power amplification factor of 9 to 12 dB (9 to 15 times). At an input power of 0.1W the output will be 1W. You must choose T1 transistor depending on applied voltage. if you have a 12V power supply then use transistors like: 2N4427, KT920A, KT934A, KT904, BLX65, 2SC1970, BLY87. At 18 to 24V power supply you must use transistors like: 2N3866, 2N3553, KT922A, BLY91, BLX92A. You may use 2N2219 at 12V but you will get an output power of 0.4W maximum.__

1 Watt Four Stage FM Transmitter - This FM transmitter circuit uses four radio frequency stages: a VHF oscillator built around transistor BF494 (T1) , a preamplifier built around transistor BF200 (T2) , a driver built around transistor 2N2219 (T3) and a power amplifier built around transistor 2N3866 (T4). A condenser microphone is connected at the input of the oscillator. __ Designed by P. Marian

1 Watt PLL FM Broadcast Transmitter - This is a 1 Watt PLL FM broadcast transmitter. The RF output varies from 500mW to about 1.2W depending on the frequency selected and RF output transistor used. Motorola 2N4427 always seems to work well. Transmitter uses CMOS
PLL VCO that prevents the frequency drifts. The frequency is selected via DiP switches. The transmitter is supplied by 12V DC and can also be powered from the battery.__

1 Watt QRP Power Transmitter - The 1 watt 20 meter QRP transmitter with VXO. This is a nice QRP transmitter that can be used in combination of one of the simple receivers. Normally these designs have only two transistors: one is the X-tal oscillator and the second the final amplifier. A good example is my first QRP rig that is also described somewhere on this site. Here the VXO (Variabele X-tal Oscillator) has a tuning range of 16 kHz. This VXO is buffered with an extra driver stage for a better frequency stability and a varicap diode is used instead of a variabele capacitor. An extra transistor is added for keying the transmitter with a low keying current. What you can do with such a simple 1 watt QRP power transmitter. This is a real low power transmitter, so do not expect that you can do everything with it but When conditions are normal, you can easily make many QSO's during one afternoon with stations with distances upto 2000 km with a simple inverted V wire dipole antenna! From Europe, I did even make QSO's across the Ocean! __

1 Watt RF Amplifier - This is a universal 1 Watt RF class C amplifier that is ideally suited for low power FM transmitters. input should be at least 100mW to achieve 1W output. it is recommended to enclose the amplifier in a metal case. __

1.3W VHF RF Amplifier 2SC1970 88-108 MHz - This RF power amplifier is based on the transistor 2SC1970 and 2N4427. The output power is about 1.3W and the input driving power is 30-50mW. it will still get your RF signal quit far and I advice you to use a good 50 ohm resistor as dummy load. To tune this amplifier you can either use a power meter/wattmeter, SWR unit or you can do using a RF field meter. __

1.5 Watt FM Transmitter - Presented here is a 1.5 Watt FM Transmitter. A transmitter is an installation in which electrical oscillations are generated by an antenna as radio waves are emitted. Although there are a variety of channels exist in terms of size, application and frequency, each transmitter is an oscillator is present (usually crystal controlled) that an electric thrill, the carrier, with a constant frequency electricity. This is followed by one or more selective amplifier stages tuned oscillation circuits, which usually frequency multiplication is performed.Modulation can occur at low power, and even strengthening of the modulated signal to the power required to reach.Modulation can also occur at high power, when the carrier signal and separately reinforced.__

1.5V FM Broadcast Transmitter - The objective of this 1.5V FM Broadcast Transmitter design is to provide a simple low-power transmitter solution for broadcasting audio from various audio sources. This transmitter accepts stereo input via two 470K resistors. Since there is no audio level control on the input, the audio level out from the source needs to be adjusted. Or, you can just add a 10k as an input level control. Transmitter's frequency, as built is tunable via spreading or compressing the coil to the desired frequency, and the coil can be glued down. if you want to make one that's tunable, it might be easiest to reduce the 18 pf capacitor and put a small trimmer capacitor in parallel with the inductor (across the reduced value capacitor). Voltage variable capacitors would be an nice alternative to a mechanical variable capacitor but they don't offer much tuning range with only a 1.5V power supply.__

1.5V Tracking Transmitter - The current draw for this tracker is 3.7mA, so the 1.5V button cell will last awhile. What the heck am I suppose to hear you ask? When your circuit is working you should see the LED flash quite fast. Take your FM radio and search for the low-beat 'humbe-humbe-humbe-etc' equal to the flash of the LED (Tony van Roon's probably around the 100Mhz). Found it? if that position is interferering with a radio station __ Designed by Tony van Roon VA3AVR

1.5w Power Amplifier - Here we put all the theory to work and present a simple power amplifier module that can be easily built with readily available components. The block diagram of the amplifier is...__ Electronics Projects for You

100 MHz Modulated RF source for FM Band - I needed a frequency reference for tuning up the RS-232 to 100 MHz RF desktop channel adapter elsewhere on this site, when I found this Saronix crystal oscillator in my junk box. A few minutes with VRStudio produced an ATtiny12 to make a tone, even fewer __ Designed by Dick Cappels

100Khz Crystal Calibrator - There is a great deal of old amateur gear which many amateurs have decided to restore and bring back to life. While much of the early amateur transceivers work just fine they usually lack a digital readout and must rely on analog dials for tuning. The problem of dial calibration is complicated by the non-linear effects of tuning capacitors. This month's circuit is a 100Khz crystal calibrator using an inexpensive microprocessor crystal and CMOS
IC 's which are readily available at Radio Shack. __ Designed by N1HFX

100m Simple Circuit FM Transmitter - Here is a very interesting and simple FM transmitter used to transmit audio in the wide range up to 100M using only one transistor. The entire circuit of FM transmitter is divided into three major stages oscillator, modulator and amplifier. The transmitting frequency of 88-108 MHz is generated by adjusting VC1. The input audio generated by microphone is changed into electric signal and is given to base of transistor T1. Transistor T1 is used as oscillator which oscillates the frequency of 88-108 MHz. The oscillated frequency depends upon the value R2, C2, L2 and L3. Transmitted audio from FM transmitter circuit can be received by standard FM receiver.__

100m Simple Circuit FM Transmitter - Here is a very interesting and simple FM transmitter used to transmit audio in the wide range up to 100M using only one transistor. The entire circuit of FM transmitter is divided into three major stages oscillator, modulator and amplifier. The transmitting frequency of 88-108 MHz is generated by adjusting VC1. The input audio generated by microphone is changed into electric signal and is given to base of transistor T1. Transistor T1 is used as oscillator which oscillates the frequency of 88-108 MHz. The oscillated frequency depends upon the value R2, C2, L2 and L3. Transmitted audio from FM transmitter circuit can be received by standard FM receiver.__

100W FM Amplifier - This Power amplifier is equipped with a bipolar transistor, the famous MRF317 As lots of FM amplifier application , the power transistor is in a C class bias. All the impedance networks (input & Output) have been determined by using the __ Designed by Michel P

100W Transmitter RF Power Amplifier 2SC2782 - This is a 6m band transmitter RF power amplifier (50 MHz) with 100W output. it used with my FT-736R and drive from 10W for the 6m SSB DX. The Building information comes from Japan CQ Magazine. The Toshiba RF bipolar power transistor is used in it. if you want to construct this rf amplifier, it's the better way if the double side PCB use for increase the grounding and current transfer. The TX power can be tune to 120W.__

10BaseT Ethernet 10GHz BPSK link - I don't know where to start on this one as it is still many single bits and bobs floating around that are still lacking other bits to bring the whole thing together. The idea that has emerged so far is to use an Ethernet card with a 10BaseT connection (kept short) to a modem which converts the signal to BPSK. For the moment no synchronization is done, and the whole Manchester encoded data with the link pulse is modulated to 480 MHz band using BPSK. The receiver is to be a simple 70 MHz BPSK demodulator regaining the carrier with a frequency doubler. Receive iF is therefor 70 MHz with 40 MHz bandwidth using a converted LNB (more on this later). A UHF / VHF splitterb combiner ensures that a single coax cable can be used to connect the RF link part to the modem. The RF link is currently a 45 cm Cassegrain antenna. A feed with OMT splits horizontal and vertical signals. The transmitter is a 10 GHz G3WDG003 upconverter by Petra Suckling G4KGC and Charles Suckling G3WDG (find out more here). __ Designed by Edward John Cardew

10GHz RS232 high speed link using FM - The poor man's high speed microwave link. Still working on this. it uses a XC9536 CPLD to link to a serial line, this chip has a built in UART, differential encoder/decoder and a manchester encoder and decoder. it just fits in a simple 36 block device but I am still battleing with the FM decoder which is to be as simple as possible. Favoured project is the DVB IP Gateway so this one has moved to the rear end of my priority list. (Sorry) __ Designed by Edward John Cardew

10-meterband transmitter oscillator for AM or CW with only two transistors - in this project, you will make a simple low-power broadcast-type circuit, using a crystal oscillator integrated circuit and an a collector modulated AM oscillator. You can connect the circuit to the an amplified microphone (no amplified microphone has a to low output voltage to work. at least 100...200mv is needed). You could also add a LF preamp stage of one transistor to allow connecting a microphone directly. __ Designed by Guy Roels ON6MU

10mW FM Transmitter Project - This type PCB is the same style of design used on the 7 Watt FM Transmitter. Take a look at the digital snap shot on the 7 Watt webpage. Notice on that picture. all of the components that are soldered onto the copper. both the components and copper are on the same side of the PCB. I decided to use this style as it was very quick and easy to change out components. during the many months of experimentation. So, there are no holes to be drilled on the PCB, except for the four mounting holes. __ Designed by braincambre500 @ yahoo.com

10W 2M CW transmitter - I use this simple CW transmitter for working through the RS13 satellite. Using just 10 Watts and a dipole at 3M above ground, I have made many contacts around Europe and across the Atlantic __ Designed by EI9GQ homebrew radio

12-meterband QRP AM oscillator transmitter using a 2N2219 transistor - in this project, you will make a simple low-power broadcast-type circuit, using a crystal oscillator integrated circuit and an a collector modulated AM oscillator. You can connect the circuit to the an amplified microphone (no amplified microphone has a to low output voltage to work (at least 100...200mv is needed). You could also add a LF preamp stage of one transistor to allow connecting a microphone directly. __ Designed by Guy Roels ON6MU